—foamable, adj. —foamer, n. —foamingly, adv. —foamless, adj. —foamlike, adj./fohm/, n.1. a collection of minute bubbles formed on the surface of a liquid by agitation, fermentation, etc.: foam on a glass of beer.2. the froth of perspiration, caused by great exertion, formed on the skin of a horse or other animal.3. froth formed from saliva in the mouth, as in epilepsy and rabies.4. a thick frothy substance, as shaving cream.5. (in firefighting)a. a chemically produced substance that smothers the flames on a burning liquid by forming a layer of minute, stable, heat-resistant bubbles on the liquid's surface.b. the layer of bubbles so formed.6. a dispersion of gas bubbles in a solid, as foam glass, foam rubber, polyfoam, or foamed metal.7. Literary. the sea.v.i.8. to form or gather foam; emit foam; froth.v.t.9. to cause to foam.10. to cover with foam; apply foam to: to foam a runway before an emergency landing.11. to insulate with foam.13. foam at the mouth, to be extremely or uncontrollably angry.[bef. 900; ME fom, OE fam; c. G Feim]Syn. 1. froth, spume, head, fizz; scum.
* * *in physical chemistry, a colloidal system (i.e., a dispersion of particles in a continuous medium) in which the particles are gas bubbles and the medium is a liquid. The term also is applied to material in a lightweight cellular spongy or rigid form. Liquid foams are sometimes made relatively long-lasting—e.g., for fire fighting—by adding some substance, called a stabilizer, that prevents or retards the coalescence of the gas bubbles. Of the great variety of substances that act as foam stabilizers, the best known are soaps, detergents, and proteins (protein). Proteins, because they are edible, find wide use as foaming agents in foodstuffs such as whipped cream, marshmallow (made from gelatin and sugar), and meringue (from egg white). The foam used to combat oil fires consists of bubbles of carbon dioxide (liberated from sodium bicarbonate and aluminum sulfate) stabilized by dried blood, glue, or other cheap protein-containing materials. Beer foam is believed to be stabilized by the colloidal constituents present, which include proteins and carbohydrates. Foaming may be undesirable, as in lubricating oils, and its prevention is not always easy. Aqueous foams usually can be broken by treatment with small amounts of certain alcohols.
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